TJ Mechanical engineering and machinery 142 TP Chemical technology 139 TA Engineering (General). Civil engineering (General) 112 TK Electrical engineering. Electronics Nuclear engineering 92 QD Chemistry 40 QC Physics 34 Q Science (General) 26 T Technology (General) 26 TH Building construction 20 TS Manufactures 18 HD28 Management. Industrial Management 12 QA75 Electronic computers. Computer science 12 L Education (General) 10 HD Industries. Land use. Labor 7 Unspecified 7 QA Mathematics 6 TD Environmental technology. Sanitary engineering 6 TN Mining engineering. Metallurgy 6 H Social Sciences (General) 5 QA76 Computer software 5 QE Geology 5 LB Theory and practice of education 4 R Medicine (General) 4 G Geography (General) 3 HD61 Risk Management 3 QH Natural history 3 TC Hydraulic engineering. Ocean engineering 3 G70.39-70.6 Remote sensing 2 GE Environmental Sciences 2 HT101-395 Sociology, Urban 2